The Police Federation criticises a fast-track training programme that aims to tackle a shortfall in the number of investigators.

Graduates will be trained to become detectives in just 12 weeks under a new plan to increase the number of investigators.

The move is part of a £350,000 fast-track training programme which could see detective numbers rise by up to 1,000 in the next five years.

It comes following a warning that England and Wales have a shortfall of 5,000 police investigators, something the HM Inspectorate of Constabulary and Fire & Rescue Services described last year as a "national crisis".

But the move has been attacked by the police union, which says it is an "insult" to its members.

Karen Stephens, Secretary of the Police Federation's National Detective Forum, said in a statement: "This news is an insult to the experienced hard-working detectives that we have left in service.

"Detective policing is in crisis and our colleagues are struggling to cope with heavy workloads and increasing demand but another 'direct entry scheme' is not the answer.

"The service and the public deserve better than detective officers who will be trained 'in a matter of months'.

"Let's not forget that detective officers deal with the most depraved and complex of crimes - this requires experience.

"Also, new, inexperienced detectives will require a lot of supervision, putting extra pressure on those already in service."

Among the reasons for the shortage in detectives are that there is growing demand for specialists in areas such as counter-terrorism and difficulty retaining people whose skills are also attractive to the private sector.

Police Now, an independent charity operating in 25 forces areas in England and Wales, will get the £350,000 for the programme in addition to £2.8m already promised by the Home Office for 2018/19.

Policing Minister Nick Hurd said: "I'm keen to get more new detectives trained up, so I'm delighted to support this innovative Police Now programme, which will bring in new talent, train detectives in a matter of months and complement other measures that the government and police are taking to keep the public safe."

The programme will include digital training, problem-solving, crime prevention and safeguarding.

David Spencer, co-founder and chief executive of Police Now, said: "As a former detective myself, I understand the positive impact that detectives can have on reducing crime, increasing confidence in communities and protecting the most vulnerable in society.

"Working with forces and the Home Office, we hope this new scheme will encourage a new group of diverse and brilliant individuals to enter the police service and contribute to the outstanding work being done by existing detectives up and down the country."

Chief Constable Matt Jukes, the National Police Chiefs' Council lead for detectives, said: "In order to mirror the changing nature of crime, we need to recruit and develop a diverse group of individuals, who will contribute to this vital area of policing and its future, underlining the critical nature of effective investigations to public confidence and trust."

It has not been decided when the scheme will start but it is not expected to be this year.